Flame position determination in well bores



Jan. 8, 1963 H. w. PARKER 3,072,184

FLAME POSITION DETERMINATION IN WELL BORES Filed May 4, 1959 PRODUCT INVENTOR. H.W. PARKER A TTORNE VS United States Patent 3,072,184 FLAME POSITION DETERMINATION IN WELL BORES Harry W. Parker, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Filed May 4, 1959, Ser. No. 810,921 20 Claims. (Cl. 166-4) This invention relates to a method of determining the progress of a combustion front thru a fuel pack in a well adjacent a combustible'carbonaceous stratum and to a novel fuel pack useful in effecting such a method.

In situ combustion in the recovery of hydrocarbons from underground strata containing carbonaceous material is becoming more prevalent in the petroleum industry. In this technique of production, combustion is initiated in the carbonaceous stratum and the resultng combustion zone is caused to move thru the stratum by either inverse of direct air drive whereby the heat of combustion of a substantial proportion of the hydrocarbon in the stratum drives out and usually upgrades a substantial proportion of the unburned hydrocarbon material.

The ignition of carbonaceous material in a stratum around a borehole therein followed by injection of air thru the ignition borehole and recovery of product hydrocarbons and combustion gas thru another borehole in the stratum is a direct air drive process for effecting in situ combustion and recovery of hydrocarbons from the stratum. In this type of operation the stratum usually plugs in front of the combustion zone because a heavy viscous liquid bank of hydrocarbons collects in the stratum in advance of the combustion Zone which prevents movement of air to the combustion process. To overcome this ditliculty and to permit the continued progress of the combustion zone thru the stratum, inverse air injection has been resorted to. By this technique, a combustion zone is established around an ignition borehole by any suitable means and air is fed thru the stratum to the combustion zone from one or more surrounding boreholes.

In situ combustion techniques are being applied to tar sands, shale, Athabasca sand and other strata in virgin state, to coal veins by fracturing, and to strata partially depleted by primary and even secondary and tertiary recovery methods.

Various techniques have been developed for igniting combustible carbonaceous strata, a more successful one comprising packing the well bore with a solid particulate fuel pack within the stratum to be ignited, igniting the charcoal at the top by means of a fusee or other igniting device and driving the resulting combustion zone thru the. fuel pack. When the stratum contiguous to the fuel pack is heated to the ignition point of the carbonaceous material therein, contacting the same with air or a mixture of air and fuel gas, either thru the ignition borehole or thru the stratum from one or more offset boreholes, initiates combustion within the stratum.

A common fuel pack comprises charcoal briquettes or small lumps which readily fill the boreholes and contact the wall thereof. Another fuel pack comprises charcoal admixed with particulate refractory or ceramic material, such as broken fire brick, pebbles of alumina, or alumina silicate pebbles which are preferably porous so that the entire fuel pack may be soaked with oil to provide ample fuel for the heating and ignition of the stratum.

In burning such a fuel pack, it is desirable and advantageous to know the progress of the combustion front thru the pack so that the relative temperatures of the surrounding stratum at different levels therein can be known and injection of air, either directly or inversely for the ignition process, can be controlled most efiiciently. Heretofore, the progress of the combustion front thru the fuel pack and the temperature of the surrounding stratum at 3,072,184 Patented Jan. 8, 1963 the Well wall has been determined by placing thermocouples at the selected levels adjacent the stratum with wires leading thru the well head to instruments which indicate the temperature in the well. This procedure is not desirable because of the excessive length of the electric wires and because of the fact that the intense heat produced by the burning charcoal frequently ruins the thermocouples and burns oil the wires leading thereto.

This invention is concerned with a method or process for determining the progress of a combustion front thru a fuel pack from either end of the pack to the other or from the interior of the pack to either end. It is also concerned with a novel fuel pack which may be utilized in this matter.

Accordingly, it is an object of the invention to provide a novel fuel pack for igniting a carbonaceous stratum around a well therein by burning the fuel pack progressively along its length and determining the progress of the advancing combustion front. Another object is to provide such a fuel pack which may be assembled as a unit at the surface and lowered into the well within the stratum to be ignited. A further object is to provide a method of determining the progress of the movement of a combustion front thru a fuel pack in a well within a stratum to be ignited without the use of expensive me chanical and electrical equipment in the well. It is also an object of the invention to provide a fuel pack and method of determining the progress of the movement of a combustion front therethru which avoids the destruction of expensive temperature sensing means. Other objects of the invention will become apparent to one skilled in the art upon consideration of the accompanying disclosure.

One embodiment of the invention consists of a fuel pack comprising an elongated mass of particulate solids containing fuel and having deposited therein at spaced intervals along its length or axis separate masses of gas forming materials, released by heating and separately identifiable in the combustion gases developed upon burn-' ing the fuel pack and egressing from the well; and progres-' sively burning the fuel pack along its axis so as to release the separately identifiable gases, whereby the same} may be observed as they appear in the effluent gases from the well to determine the progress of the combustion front thru the fuel pack.

and/or ignited, such as those utilized by the military.

Smoke bombs may be prepared by filling combustible containers with the chemicals which produce the colored smokes.

binations of chemicals which may be utilized in certain proportions to produce various colored smokes.

Pota ssium perchlorate 5 6 5 Antimony sulfide. 4 5 4 To illustrate the use of the table, a red smoke bomb may be prepared by combining one part of potassium The following table illustrates various com-- chlorate, one part lactose, and 3 parts paranitraniline red, or it may be prepared by combining potassium perchlorate, antimony sulfide, rhodamine red, and gum arabic in the proportion of 5, 4, l0, and 1 parts, respectively.

The invention is not limited to the use of smoke bombs formulated in accordance with the table, as other chemicals and mixtures of chemicals will produce similar colored gases and are operable in the process. Phosphorus, dyestuffs, etc., are also operable in the process. Neither is the invention limited to the use of chemicals and mixtures thereof which produce colored smokes, it being within the scope of the invention to utilize radioactive materials which can be released and counted automatically at the surface by a Geiger counter or similar device. Radon gas can be released by the combustion and detected by conventional means at the surface. Different quantities of the radioactive material or other material which gives off a readily identifiable gas can be released as the burning progresses thru the fuel pack.

It is within the scope of the invention to utilize any readily detectable gas not normally found in a well being ignited by a fuel pack by sealing the gas in a fusible or combustible container, such as in a thin-walled plastic bag or vessel or a glass container and detecting the gas as it appears in the effluent stream from the Well during ignition. However, smoke bombs are probably the simplest and most effective materials for use as the masses of identifiable materials to be placed in the fuel pack.

A more complete understanding of the invention may be had upon consideration of the accompanying schematic drawing of which FIGURE 1 is an elevation in partial section thru a Well in a carbonaceous stratum to be ignited and FIGURE 2 is an elevation of a preferred form of a fuel pack made in accordance with the invention.

Referring to FIGURE 1, a stratum 10 is penetrated by a borehole 12 which is provided with a casing 14 extending to the approximate upper level of the stratum. Borehole or well 12 is filled to the top of the stratum with charcoal briquettes 16. A well head 13 is provided on the upper end of casing 14 and a production line 20 extends thru the well head and may continue down to a level adjacent the upper end of the fuel pack. Within fuel pack 16 are positioned a series of smoke bombs 22, 23, 24, and 25, preferably placed along the axis of the fuel pack at selected intervals, such as every two to 25 feet, To illustrate, device 22 gives off a blue smoke, 23 gives off a green smoke, 24 a yellow smoke, and 25, a red smoke so that if device 22 is placed feet below the top of the fuel pack and the other devices are placed at foot intervals, it will be known that the combustion zone has progressed 5 feet thru the pack when blue smoke appears in the effluent from the Well, feet when green smoke appears, 25 feet when yellow smoke appears, and 35 feet when red smoke appears, etc. In igniting a thick stratum, additional colors may be utilized or the colors in the first series may be repeated in the same order or in any other order in successive smoke bombs. The smoke bombs may be spaced equidistant from each other or at any selected non-uniform spacing.

Numeral 28 designates an ignitor with a fuse 29 extending thru the well head so that the upper end thereof may be ignited to convey the spark to the ignition device. It is also feasible to drop an ignited fusee such as a railroad flare or other device containing self-oxidizing or incendiary material onto the fuel pack. Ignition is also effected in many instances by dropping a mass of burning charcoal onto the top of the fuel pack and injecting air thereto, either thru casing 14 or thru one or more offset wells serving as air injection Wells. It is not essential to ignite the fuel pack at the top but on the contrary the same may be ignited at the bottom by an ignitor 32 or, at an intermediate section, by an ignitor 39. It is also feasible to ignite the fuel pack at both ends so that the same bur-us toward the middle from each end. In one type of ignition, a conduit is positioned in the well extending from the well head to the bottom of the hole, with the charcoal packed around the conduit, and dropping a railroad fusee down the conduit into the charcoal at the bottom of the well and injecting air thru the conduit until the entire lower end of the fuel pack has been ignited; thereafter withdrawing the conduit so that the lower end is at a level adjacent the top of the fuel pack, feeding air to the combustion Zone thru the stratum, and exhausting combustion gases thru the conduit. Air is supplied to the fuel pack thru the stratum by injection thru offset injection wells. In order to facilitate the ignition of the stratum, it is very effective to incorporate in the injected air a concentration of fuel gas, such as L.P.G., or normally gaseous hydrocarbons, such as natural gas, in the range of about 1 to 3 volume percent.

Whether igniting the fuel pack at the upper end or the lower end, it is essential to vent the combustion gas thru the ignition well so as to be able to detect the readily identifiable gas (smoke) given off by the various devices disposed in the fuel pack. it is therefore essential to inject air either thru the bottom of the well or thru the stratum into the well from offset injection wells. In instances where the bottom of the fuel pack is initially ignited the smoke bombs or other devices must be encased in containers which maintain the smoke-giving material intact until the container is within the flame or combustion area. Containers made of several layers of Wax paper are eifective as are various plastic materials which have a melting point of at least 400 or 500 F.

In FIGURE 2, a charcoal pack 4%} is encased in a sheath 42 made in the form of a generally cylindrical sack of diagonal weave and loosely woven so that when suspended by a rope or cable 44 the sack becomes elongated and when resting in the borehole the sack becomes expanded to contact the Walls thereof. The diameter of the sack can be adjusted so that when filled with charcoal or other solid fuel and suspended on rope 44 the diameter of the fuel pack is less than the well diameter by an inch or two rendering it easy to lower the fuel pack into the well. As in the fuel pack shown in FIG- URE I, smoke bombs 23, 24, 25, etc., are positioned at selected intervals along the axis of the pack and an ignitor 28 is positioned in the upper end thereof. Of course, this ignitor may be positioned in the lower end and it may be omitted entirely with the ignition being effected by dropping hot charcoal or a burning flare onto the top of the pack after positioning same in the well.

Sheath 42 may be fabricated of any loosely woven material such as cotton, wool, rayon, nylon, or other synthetic fibers. It is also feasible to fabricate the sheath of heavy perforate paper or other material which can be burst by dropping the fuel pack several feet onto the bottom of the hole. It is preferable to fabricate the sheath of combustible materials which do not interfere with the ignition and recovery of hydrocarbon material from the stratum.

In applications in which a thick stratum is to be ignited, it is desirable to pack the borehole Within the stratum to be ignited with a plurality of fuel packs 40, each encased in a sack or sheath. This avoids unduly extended and. cumbersome sheathed packs. However, in such applications the well Within the stratum to be ignited may be packed by dropping successive portions of charcoal (or other solid fuel) down the well or depositing same at the well bottom by lowering the fuel in a cylindrical container with a releasable bottom. Regulated amounts or charges of charcoal are intermittently placed at .the site of the ignition, withsmoke bombs being positioned in each fuel charge or between charges.

It is within the scope of the invention to utilize only one or two indicating devices or smoke bombs in the fuel pack. It may be desirable to know when the cornbustion Zone has reached a specific level in the stratum,

such as the 5 foot level below the top or the 5 foot level above the bottom of the pack, or both.

Certain modifications of the invention will become apparent to those skilled in the art and the illustrative details disclosed are not to be construed as imposing unnecessary limitations on the invention.

I claim:

1. A fuel pack for burning in a well comprising a substantially cylindrical pack of particulate solids containing fuel and having disposed therein at spaced intervals along its length separate masses of different gas forming materials, releasable by heating and separately identifiable in the combustion gases developed upon burning said fuel in said well and indicating the progress of combustion thru said pack.

2. The fuel pack of claim 1 enclosed within a perforate sheath adapted for lowering into a well.

3. The fuel pack of claim 1 including an ignitor therein.

4. The fuel pack of claim 1 wherein each succeeding mass in the order of burning along said fuel pack produces a gas of different color from the immediately preceding mass.

5. The fuel pack of claim 1 comprising charcoal.

6. The fuel pack of claim 1 comprising charcoal andceramic pieces.

7. The fuel pack of claim 1 comprising porous ceramic pieces soaked with oil.

8. In a well within a combustible carbonaceous stratum, an elongated fuel pack of particulate solids, said pack extending along a substantial section of said stratum; and separate masses of different gas forming materials, re leasable by heating and separately identifiable in the combustion gases developed upon burning of said fuel pack from end to end disposed at spaced intervals along the length of said fuel pack whereby the progress of the combustion zone moving thru said pack is indicated.

9. The fuel pack of claim 8 wherein each succeeding mass in the order of burning along said fuel pack produces a gas of different color from the immediately preceding mass.

10. The fuel pack of claim 9 including an ignitor there- 11. A method of determining the progress of movement of a combustion front thru an elongated fuel pack comprising particulate solids containing fuel disposed in a well which comprises placing in said fuel pack, at spaced intervals along its length, separate masses of gasforming materials released by heating and separately identifiable in the combustion gases developed upon burning said fuel pack; progressively burning said fuel pack along its axis by igniting and supplying oxygen thereto so as to release the separately identifiable gases; and separately identifying said gases as they appear in the efiluent gases from said well so as to determine the progress of said combustion front.

12. The method of claim 11 wherein each succeeding mass in the path of the combustion front produces a gas of different color from the immediately preceding mass.

13. The process of claim 11 comprising igniting said pack at one end and progressively burning same toward its opposite end.

14. The process of claim 11 comprising igniting said pack at an area intermediate the ends and progressive- 1y burning same toward its ends.

15. The process of claim 11 comprising igniting said pack at each end and progressively burning same toward its center section.

16. The process of claim 11 wherein said fuel pack comprises charcoal.

17. The process of claim 11 wherein said fuel pack comprises charcoal and ceramic pieces.

18. A method of determining the progress of movement of a combustion front thru an elongated fuel pack of particulate solids disposed in a Well which comprises placing in said fuel pack at a selected locus therein a mass of gas-forming material releasable by combustion of the adjacent fuel to form a readily identifiable gas in the resulting combustion gases; progressively burning said pack along its length by igniting and supplying oxygen thereto so as to release said gas; and identifying said gas as it appears in the effluent combustion gases.

19. A fuel pack for burning in a well comprising an elongated non-explosive mass of particulate fuel having a transverse cross-section adapted to fit into a Well bore coaxially therewith and a small mass of colored-gas-forming material spaced substantially from the ends of said pack, said material being decomposable to form said colored gas by heat released by burning the adjacent fuel particles, and said pack being permeable to gas flow therethru both longitudinally and transversely; and means for igniting said pack adjacent the upper end thereof.

20. The fuel pack of claim 19 enclosed in a perforate sack adapted for lowering into a Well.

References Cited in the file of this patent UNITED STATES PATENTS 1,510,926 Kaiser et al. Oct. 7, 1924 1,645,206 Stevens Oct. 11, 1927 2,398,571 Young Apr. 16, 1946 2,650,539 Greene Sept. 1, 1953 2,670,047 Mayes Feb. 23, 1954 3,004,597 Marx et al. Oct. 17, 1961 

11. A METHOD OF DETERMINING THE PROGRESS OF MOVEMENT OF A COMBUSTION FRONT THRU AN ELONGATED FUEL PACK COMPRISING PARTICULATE SOLIDS CONTAINING FUEL DISPOSED IN A WELL WHICH COMPRISES PLACING IN SAID FUEL PACK, AT SPACED INTERVALS ALONG ITS LENGTH, SEPARATE MASSES OF GASFORMING MATERIALS RELEASED BY HEATING AND SEPARATELY IDENTIFIABLE IN THE COMBUSTION GASES DEVELOPED UPON BURNING SAID FUEL PACK; PROGRESSIVELY BURNING SAID FUEL PACK ALONG ITS AXIS BY IGNITING AND SUPPLYING OXYGEN THERETO SO AS TO RELEASE THE SEPARATELY IDENTIFIABLE GASES; AND SEPARATELY IDENTIFYING SAID GASES AS THEY APPEAR IN THE EFFLUENT GASES 